GREENFIELD — With the 56-year-old Greenfield High School serving as a backdrop — and with a score of its alumni scattered throughout the audience — school, town and state officials ceremoniously broke ground Monday on the new $66 million high school.

It was a project, speakers said, that was never a certainty. When the Greenfield School Building Committee formed three years ago, it was charged to consider renovation options for the crumbling school, not new construction. And even when the final proposal was formed, it still required a large state contribution and increased local taxes to fund it.

But the Massachusetts School Building Authority agreed to extend its maximum amount of aid (80 percent of eligible funds, for about $42 million). Then, a year ago this Wednesday, Greenfield residents voted to pick up the rest.

And in the time that has followed, the School Building Committee has worked with consultants to complete interior and exterior designs, selected its construction manager and began laying plans for the next two years of construction.

“It’s quite a collaboration that takes place between friends and neighbors and strangers,” said Mayor William Martin, to a crowd of about 100 under a tent in front of the high school.

Martin spoke of ground-breaking and ribbon-cutting ceremonies past — including one on this spot nearly six decades ago, attended by then-U.S. Sen. John F. Kennedy.

“The leaders have changed and the process has changed, but the commitment has not changed,” said Martin. “Every 50 years, the citizens and residents in this community rally together and find some way, somehow to get it done when it has to be done.”

The message of partnership — between town and state, between committees and boards — was echoed repeatedly Monday in the words of the nine who took to the microphone.

Massachusetts Treasurer Steven Grossman said that the involvement of the MSBA — which is funded by a penny of the state’s sales tax — ensures that “every dime ... is going to be spent wisely.”

And Sen. Stanley Rosenberg, D-Amherst, said that the only way to build a “state-of-the-art-school” is if the state’s residents work with one another.

“The next time you’re driving on the Turnpike or Route 2 closer to Boston, and you’re stopped at a stoplight, look out the window at the driver in the car next to you and give him a big wave and say, ‘Thank you,’” said Rosenberg.

For others, Monday marked the start of a new chapter for Greenfield High School. Officials spoke of new classrooms that students will begin using as soon as next fall, as well as the auditorium — the only space from the current building that will be incorporated into the new school.

“I find myself at a loss for words of what this school will mean in the future to Greenfield as a community, to the students and to their education,” said Superintendent Susan Hollins. “The new school will have the most current science labs possible. It will have rooms with ... interactive technology.”

It will be a big change from the current building, which saw problems almost immediately, said guest speaker Betty Nee, an alumna and longtime front office worker who remembers well the last time Greenfield had a brand new high school.

A major rainstorm early on caused water to drip into the office, recalled Nee, forcing the staff to strategically place several metal pails.

“At one point, we even put some plants in them,” she said, prompting a roar of laughter from the audience.

Also speaking Monday were Rep. Paul Mark, School Building Committee Chairman Keith McCormic, Town Council Vice President Mark Wisnewski and MSBA Executive Director Jack McCarthy.

Town councilors and school board members attended and posed with shovels for photos after the ceremony.

Shawmut Design and Construction crews worked in the background throughout the ceremony. The firm has been on school grounds since earlier this month.

Groundbreaking ceremony guests were among the last to use the parking lot for general use. It was shut down Monday to make room for the construction site, forcing parents to drop their students on the side streets off of Silver Street.

Greenfield Police officials were on hand to assist with traffic and said Monday that there were some complaints but no major issues.